Field of the Disclosure
The present disclosure relates in general to antennas, and more specifically, to compact and directional planar inverted-F antennas (PIFAs) integrated in artificial magnetic conductor metamaterials which may be used for wireless power transmission.
Background
Wireless power transmission may include a transmitter for forming and directing radio frequency (RF) waves towards a receiver which may convert RF waves into usable power for charging or powering an electronic device. The receiver may be integrated in the electronic device (e.g., a smartphone, a tablet) or may be in the form of cases that may be operatively coupled with the electronic device for suitable charging or powering. The transmitter may be an antenna array that may include N antennas which may be directional.
The antenna array may be controlled by computer hardware and software in order to broadcast a wireless signal towards the receiver. Amplitude and phase among other properties of the transmitted RF waves may be tuned by the computer hardware and software to form constructive and destructive interference patterns generating pockets of energy in a 3-dimensional shape from the constructive patterns, and null spaces from the destructive patterns to aim the pockets of energy to specific receivers.
The number of antennas in the antenna array may vary in relation with the desired power range and transmission capability of the transmitter. The more antennas the wider the range and higher the power transmission potential available at the transmitter. More antennas may additionally enable the transmitter to target more receivers at once. Directional antenna designs that can be integrated in transmitters may include Yagi, log-periodic, corner reflectors, and parabolic antennas, among others.
However, size may be one important factor that may impact the number of antennas that can be integrated in the antenna array for the transmitter. Designers often look for the optimal combination of size and performance in the antennas integrated in the transmitter, where the performance is usually hampered when size is reduced.
Planar inverter F antennas (PIFA) may be fabricated in small form factors that may allow for dense antenna arrays. However, PIFA antennas' radiation pattern is commonly omnidirectional, which might mean than a transmitter including an antenna array of PIFA antennas may waste transmitted power. Additionally the omnidirectional radiation patterns may hinder the transmitter ability to focus the transmitted RF waves to specific receivers.
For the foregoing reasons, there is a need for a directional antenna that may enable for the construction of tightly packaged antenna arrays that may render reasonable small sizes of antenna arrays while keeping a suitable performance.